Dual-stage switching system for lithographic machine

A dual-stage switching system for lithographic machine, the system comprising a first wafer stage to be operated in an exposure station and a second wafer stage to be operated in a pre-processing station, with the two wafer stages being arranged on a base;

• wherein four 2-DOF driving units are provided near the edges of the base respectively and are movable in X direction and Y direction individually, the two wafer stages are arranged within a space surrounded by the four 2-DOF driving units and are suspended above an upper surface of the base via air bearings;
• each of the 2-DOF driving units comprises an upper linear guide, a lower linear guide and a guiding sleeve, with the upper linear guide and the lower linear guide mounted to the guiding sleeve and being perpendicular to each other;
• the 2-DOF driving units and the wafer stages are coupled by air bearings which are preloaded by permanent magnets and/or by vacuum;
• and
• each wafer stage is moved in X direction or Y direction by the upper linear guide of one of the 2-DOF driving units which applies a pushing or pulling force to this wafer stage, while the lower linear guide of a neighboring 2-DOF driving unit performs synchronized following movement with that upper linear guide at the same speed and in the same direction.